The present invention relates to a novel basic concept for the rapid, random-access retrieval of micrographic and date images stored on plural windowed discs. The concept can be implemented to provide a variety of specific devices.
The term "windowed" disc refers to an optically clear area on each disc that characterizes this type of invention. The essential principle is that aligned clear windows in plural discs form a viewing column through which the stored information on any single unaligned disc may be seen.
The present invention shares some aspects of the windowed disc concept with prior art. Examples of the prior art are the U.S. Pat. Nos. 2,989,904 to Braggs et al; 3,421,802 to Irazoqui; 3,959,801 to Booth; 4,132,469 to Harvey and 3,975,745 to Pick. However, it differs greatly from the prior art in its general concept and the apparatus for implementing it.
The primary advantage of windowed disc devices over related disc devices reduces the amount of space utilized between the discs, which greatly affects the overall storage density of the device. Optical retrieval devices based on the principles of magnetic disk storage devices have no window and consequently must insert read heads between discs (Booth; Pick). Providing each disc with an optically clear window allows discs to be stored proximately.
Prior windowed disc devices may be divided into two groups depending on the function performed by the disc window. In one group, the viewing column formed by the aligned windows is used to allow passage of an optical head from one disc position to another (Braggs; Harvey). In this group, the disc windows must be open at the rim in order to allow lateral insertion of the optical head into the viewing column. In the second group, the viewing column is used to allow passage of the information-reading optical beam only, which is directed from the ends of the viewing column (Irazoqui). In this group the disc rim at the window location may be closed since no physical components are inserted into the viewing column. The present invention belongs to the latter group.
Two features of the present invention distinguish it from all other prior windowed disc art. First, it provides mechanisms that access discs containing plural concentric levels of images; all prior art windowed discs contain only a single ring of images.
Second, it provides mechanisms that address a plurality of object planes (disc positions) while maintaining a constant aerial image plane, thereby enabling retrieval with no relative motion between the disc stack, the chassis and the primary viewing element (lens, video pickup, change coupled device). Prior art devices either use a single object plane or fail to disclose means for achieving plural object planes.
The various prior art devices have additional problems which can be solved or alleviated by the present invention. For example, the present invention can:
record as well as play; PA1 retrieve any image in 100,000 in 1/2 second; PA1 store more than one type of information on the same storage medium, allowing both eye-readable and machine-readable playback from the same machine; PA1 store multiple media types (black-and-white and color photo emulsions, eraseable laser-ablative optical data disc media) on the same disc or in the same cartridge, allowing retrieval of a wide range of information types from the same machine; PA1 avoid loss of storage area due to peripherally-increasing bit size (as required in constant-velocity disc devices); PA1 avoid loss of storage area due to on-medium servo guidance tracks or spaces (as required by micro bit size optical disc devices); PA1 increase stack volume-density by storing discs contigously (as cited above); PA1 increase stack volume-density by reducing the thickness of the discs using integral constructions of transparent substrates and emulsion rather than the multi-piece opaque substrate constructions used by prior art); PA1 facilitate the placement and removal of discs in cartridges; PA1 interface with any type of display or transmission equipment capable of utilizing an aerial image (ocular lens, projection lens, video pickup, CCD facsimile scanner, etc.); PA1 avoid the coding of image location on the image medium (for example, micrographic "blip" coding); PA1 operate under total computer control of its various electromechanical components (computer-driven rather than "computer-assisted-retrieval", CAR); PA1 store unitized volumes of information far beyond the unit capacities of existing equipment (for example, beyond the 80-image limit of carousel slide projections, beyond the 200-foot roll film cartridge capacity of current CAR micrographic systems and beyond the 500 megabyte limit of magnetic disc drives); PA1 access large volumes of information without manual operator intervention (for example, no roll film cartridge swapping, no exchanging of magnetic disc assemblies); PA1 largely avoid "autofocus" adjustments by maintaining precise positioning of all discs at all times; can also use its existing optical adjustment system for autofocus purposes if needed.
There and other advantages of the present invention will become more apparent with consideration of the following description.